From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=52653 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OOnaL-0003k9-D3 for qemu-devel@nongnu.org; Wed, 16 Jun 2010 04:02:58 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OOnaK-00008e-45 for qemu-devel@nongnu.org; Wed, 16 Jun 2010 04:02:57 -0400 Received: from fmmailgate02.web.de ([217.72.192.227]:36288) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OOnaJ-00008O-OC for qemu-devel@nongnu.org; Wed, 16 Jun 2010 04:02:56 -0400 Message-ID: <4C18852C.5010209@web.de> Date: Wed, 16 Jun 2010 10:02:52 +0200 From: Jan Kiszka MIME-Version: 1.0 References: <20100516152304.10489.35592.malonedeb@potassium.ubuntu.com> <20100616070748.20899.45040.malone@wampee.canonical.com> <4C187FD7.5080601@web.de> <4C188203.5060402@web.de> In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig9731D6FFFC074292A800C00F" Sender: jan.kiszka@web.de Subject: [Qemu-devel] Re: [Bug 581353] Re: qemu doesn't stop execution upon hitting a breakpoint List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jun Koi Cc: chimeranet89@gmail.com, qemu-devel@nongnu.org This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig9731D6FFFC074292A800C00F Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Jun Koi wrote: > On Wed, Jun 16, 2010 at 4:49 PM, Jan Kiszka wrote: >> Jun Koi wrote: >>> On Wed, Jun 16, 2010 at 4:40 PM, Jan Kiszka wrote= : >>>> Jun Koi wrote: >>>>> On Wed, Jun 16, 2010 at 4:07 PM, Alfredo Mungo wrote: >>>>>> Same thing happens to me, same versions as above.. I must turn to >>>>>> another app to accomplish my work while awaiting for a bug-fix, th= e code >>>>>> is perfectly executed but while gdb hits the breakpoints qemu goes= on.. >>>>>> >>>>>> -- >>>>>> qemu doesn't stop execution upon hitting a breakpoint >>>>>> https://bugs.launchpad.net/bugs/581353 >>>>>> You received this bug notification because you are a member of qem= u- >>>>>> devel-ml, which is subscribed to QEMU. >>>>> i think this bug has been fixed in 0.12.4. have you tried that?? >>>> Or this is a well-known gdb deficit: if the bootloader operates in >>>> real-mode, you have to set two breakpoints, one at the linear addres= s to >>>> make qemu catch it, and another one at the segment offset to avoid g= db >>>> skipping the exit due to ip !=3D bp-addr. >>>> >>>> gdb is still fairly restricted when it comes to system-level debuggi= ng, >>>> specifically as it lacks support for special x86 registers and the >>>> segmented addressing mode. >>> what do you mean by "it lacks support for special x86 registers" ? >> idtr, gdtr, ldtr, tr, crX - to name the most important ones. >=20 > do you mean gdb has no command to show the values of these registers? > or you mean it doenst have anyway to get notified when these registers > are modified? (i dont see how this is useful for debugging, anway) Both: Neither supports gdb them as part of its register set nor does the remote gdb protocol transport them. You need this for segmented addressing, either in real mode (linear address =3D segment * 16 + offset) or in segmented protected mode (less common in modern OSes, but at least still used for per-CPU variables in Linux). And you need a way to detect the current operation mode at all to switch between 16/32, and 64 bit registers (set arch i386 vs. i386:x86-64). You don't need all this for application-level debugging, and that's why gdb lacks it so far. Jan --------------enig9731D6FFFC074292A800C00F Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (GNU/Linux) Comment: Using GnuPG with SUSE - http://enigmail.mozdev.org iEYEARECAAYFAkwYhS0ACgkQitSsb3rl5xTrTACeNZHdZqHTBgHif2cmwra38/Yt ObgAnjhvZ8J3wTZISKPujJQSnc28JAS0 =Q2e8 -----END PGP SIGNATURE----- --------------enig9731D6FFFC074292A800C00F--